[Barry]

Anyone know what's in cold-packs, the type that contain a very thick, gelatinous material? 

I'm making homemade cold-packs. 
So far I've tried a mixture of propylene glycol, water, & guar gum for the filler.  (put it in polybags, seal the end)

The gum clumps up into globules, and at best, makes the solution syrup-like.  Not even close to being gelatinous.  Seems like the only way it could possibly become gelatinous, would be if I used huge amounts of the gum, and that's not cost-effective.

Wonder if I tried glycerine, water, and cellulose, if I could get a strong, thick, gelatinous mixture?

[Arkcon]

Funny.  I had no idea what the gel in gel-type packs was, but a quick Google suggested isopropanol or dish washing soap.  Maybe you could try them both?  Mixing soap and water and alcohol will make a gel.  At a guess, a cellulose based gel could maintain a scaffold when frozen, but I don't have a citation for that one, just a wild guess.  Or maybe the famous kid's experiment -- slime from elmer's glue and borax will maintain it's viscosity during freeze-thaw.

[Barry]

I'm trying to duplicate the material found in the 'cryobags' sold on the Ezy Wrap site.  (seems to be down today) 
http://www.ezywrap.com/c-165-cold-therapy.aspx

Anyhow, this stuff is so thick and gelatinous and clingy, you have to manually scoop it out of the bag to remove it. 

The cold-packs I've made so far (propylene glycol, water, & guar gum) are just syrip-like, and once they begin to thaw, the material sags and collects at the bottom of the bag, whereas the Ezy Wrap bags' gel stays more or less evenly distributed throughout, even as it thaws.

Simply put, I need to make a truly thick, gelatinous material that will stay suspended throughout the bag, not settle at the bottom upon warming.


I'm almost certain they're using glycerin in their bags as the main component.  But not sure what they're using to 'thicken' it up.

[fledarmus]

Here is one description of a gel-pack, no idea whether it is actually being sold or who it is being sold by - apparently they are using a commercially available proprietary acrylamide polymer to maintain the gel. This is from US patent 5,148,804.